August 23, 2017
Under the Standard AS/NZS 1716, filters used in respirators are required to meet certain performance levels to achieve a classification – this then allows determination of its suitability for use against specific contaminants at various concentrations as explained in AS/NZS 1716.
PARTICLE FILTERS
Filters are tested for capture efficiency in the laboratory using a salt aerosol challenge agent. Under specified test conditions the amount of these particles that break through the filter is measured which allows classification of the filter. Under the Standard AS/NZS 1716, there are three classes of particle filters.
CLASS | COLOUR | APPLICATION |
P1 | White | Used for mechanically generated particulates e.g. dust, mists, flour and silica. This class of filter is suitable for relatively “large” particles (>1 micron) released in mechanical operations e.g. sanding, drilling, cutting, sawing and crushing. |
P2
White
Used for mechanically and thermally generated particles e.g. welding fume. This class of filters has a higher capture efficiency to be able to effectively filter the many sub-micron sized thermally generated particles. The P2 is also the class of filter recommended for specific infection control application e.g. H1N1 influenza 09 (Human Swine Influenza), Tuberculosis (TB) or other infectious diseases, where they can capture biologically active airborne particles and aerosols under specified conditions.
P3
White
Used for mechanically and thermally generated sub-micron particulates, viruses, bacteria, and highly toxic materials e.g. Beryllium, radioactive particles. A P3 filter offers higher protection than a P2 filter however this is only achieved when the P3 filter is used in combination with a full face respirator.
GAS & VAPOUR FILTERS
Gas/Vapour filters are produced specifically for use against various gases and vapours and are tested and marked accordingly. AS/NZS 1716 uses a code/colour classification system to identify the different types of contaminants these treated carbon grains will capture.
CLASS | COLOUR | APPLICATION |
A | Brown | Organic vapours with boiling points > 65C |
AX | Brown | Organic vapours with boiling points <65C |
B | Gray | Inorganic gases |
E | Yellow | Acid gases |
K | Green | Ammonia |
Hg | Red | Mercury |
G | Brown | Organic compounds with low vapour pressure |
All gas/vapour filters are also rated for their absorptive capacity. In increasing capacity there are Class Aus, Class 1, Class 2 and Class 3 filters, for example:
A1/B1/ E1 Filter, where ABE represents the type of contaminants the filter will capture, and 1 represents the class of absorptive capacity.
The higher the class, the higher and longer the concentration they are able to deal with when fitted on the right type of respirator. By combining the two types of filters (particle and gas vapour), you can geet combination filters like A1P2, BAusP1 or A2B2E2K1P3.